Synthesis of 3-Amino-4-methylidene-2-azetidinone via a Thermal Elimination Reaction.-The probably antimicrobial active title compound (IX), in its N-protected form, is synthesized in 10 steps starting from the trans-azetidinone (III), which is exclusively formed in the (2 + 2) cyclization of compounds (I) and (II). Attempted deprotections with CF3COOH as well as H2/Pd do not give the desired title compound, thus requiring further studies. -(KIM, S. H.; NAM, G.; JANG, E. S.; CHI, D. Y.; KIM, J.-H.; Bull. Korean Chem.